Primary cardiac tumors are rare at all ages, and especially so in childhood, where the most prevalent type of benign cardiac masses are rhabdomyomas followed by fibromas, both of which have a predilection for ventricular septum. We report an unusual case of a tumor involving the ventricular septum in an asymptomatic 17-year-old adolescent who has been known to have this tumor for 10 years. The use of multiple imaging included myocardial contrast two-dimensional echocardiography, real time three-dimensional echocardiography (with and without myocardial contrast), and magnetic resonance imaging supported the diagnosis of cardiac rhabdomyoma.